The present invention relates to drain cleaner compositions. More specifically, the invention is directed towards a drain cleaner having a coating which delays the onset of the exothermic reaction which occurs when alkali metal hydroxide reacts with water such as in crystal-type, alkali metal hydroxide based drain cleaners.
Drain cleaner compositions are well known in the art. Solid drain cleaner compositions are usually based upon strong caustics that generate heat upon addition to water in order to liquefy fats and greases and to dissolve hair and soap curd most usually responsible for plugging up the drain. The caustics attack mold, slime, food particles and the like to further aid in opening up the drain.
Because of the speed and the exothermic nature of the reaction, care must be taken in handling the known drain cleaner compositions. They sometimes contact water prior to their application in the drain as for example during storage. Many attempts have been made to address this problem by including the combination of binders in the drain cleaner pellet as shown in U.S. Pat. No. 4,058,474 and the use of coatings as described in U.S. Pat. No. 4,664,836. As pointed out in the latter patent, very water soluble coatings allow the hydroxide to dissolve quickly but provide less protection against atmospheric moisture during storage while water insoluble coatings require some mechanism to cause the coating to break and release the hydroxide. Neither approach is entirely satisfactory.